Ghana international Andre Ayew limped off on his debut for West Ham United.
The Hammers were beaten 2-1 by Chelsea in their English Premier League opener at the Stamford Bridge.
The 26-year-old suffered a thigh injury in the 32nd minute and was replaced by Gokhan Tore.
He is set to undergo surgery tomorrow to ascertain the extent of his injury.
Ayew joined West Ham on a record fee of £20m from Swansea City this summer.
